The instant invention relates to a carrier rack lift assembly for use with pick-up trucks, flat bed trucks and trailers and more particularly to a lift assembly having telescoping support members that can be raised to any desired height within a specified range for supporting and maintaining a wide variety of loads.
The well known truck racks are used to increase the usefulness of pick-up trucks, flat bed trucks and trailers. Many of the prior art racks must be permanently fastened to the truck bed and are available at one specific height. Some may be adjustable to two or three preset heights while a few may exhibit a wider range of adjustability. In most of the adjustable prior art racks, any change in the height of the rack must be accomplished when there is no load resting on the upper portion of the rack and require more than one person to effect the change. The prior art racks are, in actuality, merely support frames with limited versatility. They are not designed to be completely height adjustable nor are they designed for adjustability under heavy loads. Changes in height cannot be made by one person. None of the prior art rack assemblies are meant to secure the interior of the truck bed or to provide any other functions.
Hart, in U.S. Pat. No. 2,720,414, describes a rack that is made in sections and is mounted on the body of a pick-up truck. All four sides of the rack are horizontally adjustable to fit a variety of truck bed lengths. Each of the four vertical support posts have one height adjustable member which can raise the upper horizontal supports high enough so that long boards can be extended over the cab of the truck. Both horizontal and vertical adjustments are made possible with outer tubes having multiple openings along their open ends and inner tubes with one opening. The inner tubes are inserted into the outer tubes to the desired distance and secured in place with pins. A load being supported on the rack must be completely removed in order to alter its height and more than one person would be needed to accomplish this. The rack cannot be collapsed and, if not needed, the entire rack must be removed from the truck bed and stored elsewhere.
In U.S. Pat. No. 5,190,337, McDaniel discloses a collapsible rack for use within the bed of a pick-up truck. The rack has four vertical legs, each having two segments connected by a knuckle joint which enables the legs to be folded downward when the rack is not in use. The bottom segments are pivotally mounted to base plates anchored to the truck bed and which run along its horizontal axis. An angled brace extending from mid base plate to the top of each rear leg gives added support to the frame when elevated. There is a side rail on each side of the rack mounted at the top of each pair of legs. A frame extension extends from each side rail over the cab to support long loads. The entire frame collapses flat along the sides of the truck bed when not in use and the parts of the rack fit within channels in the side rails for protection from the elements. The rack can only be used in the one elevated orientation and is stored in the collapsed orientation which takes up space in the truck bed.
An adjustable rack is taught by Berkich in U.S. Pat. No. 5,476,301. The height of the four vertical supports can be adjusted by raising the upper segments having a series of apertures and securing their positions with pins or bolts through corresponding apertures in the lower segments. The height of each support must be adjusted individually making it difficult to do while a load is supported on the rack. There are extensions of upper side rails over the cab that can reach as far as the front bumper, as well as rearward extensions beyond the tailgate. When the vertical supports are in the lowermost positions they rest below the sides of the truck and a cover, cap or camper can be used within the truck bed. This rack is not practical if the height of the rack must be changed with any frequency or with a load in place.
James, in U.S. Pat. No. 5,628,540, discloses another pick-up truck utility rack. The four vertical supports of this rack are mounted on the upper surfaces of the sides of the truck bed. There is a panel attached to the two forward supports which is hinged to pivot downward to form a shelf with a brace to limit the movement to 90xc2x0. A movable lower rail is attached to the rear supports and can be lowered to the level of the shelf with which it forms a second level to support a load. An extension can be used over the cab so that long boards can be carried. The vertical supports are of fixed length and once set in place remain stationery. Any load placed at mid-level can only be of the dimensions of the truck bed.
A camper for mounting in the bed of a pick-up truck is taught by Eckman et al. in U.S. Pat. No. 3,743,345. The camper has four telescoping corner support posts, each formed in three tubular sections that are square in cross section and have multiple apertures long their lengths. The supports are raised to the desired height and each segment is secured with a pin that is kept in place by a spring detent. There is a wood reinforced plastic roof that may be used in a horizontal orientation or it may be raised from one side to provide a slanted roof. A notched slotted bracket with a sliding bolt is used to set the angle of the roof. The roof height may be set at many different levels due to the many apertures in the tubular segments, but each post must be set individually. Once the roof is in place, adjustment to a different height may require more than one person. Canvas side flaps form the vertical walls of the camper. Horizontal arms secured to the uppermost sections of the corner support posts may be used to extend the camper space and can be covered by the canvas flaps. The entire camper unit can be removed and used as a tent independent of the truck. The canvas flaps only provide shelter from the elements but do not secure the interior of the camper. There is no way to raise all of the posts at the same time.
A lumber rack-camper as taught by Ingram in U.S. Pat. No. 5,423,587 has a non-adjustable rack frame which can be reversibly attached to the sides of a pick-up truck. There is an over-cab extension for carrying long boards and several cross rafters are supported on the tops of the corner vertical supports and intermediate posts supported on side frame members. A flexible cover is placed over the rafters to enclose the camper. The front of the cover fits over the extension and is supported by angled braces to proved and an air dam so the truck can travel at highway speeds while the camper cover is in place. Each side panel of the cover can be rolled up or down independently, but they do not secure the interior compartment. The corner supports are not adjustable.
Modifications to the side walls of a pick-up truck to provide secure storage compartments are taught by Clare et al. in U.S. Pat. No. 6,033,002. The storage compartments are hidden and built into the side walls. They are accessed through top mounted doors. A carrier rack that can be collapsed into the truck bed is also disclosed. The rack has a swivel mounted cab extension that folds backward for storage. The four supports for the rack may have two or three nesting segments and are adjustable by means of apertures and pins. When collapsed into the truck bed the rack cannot be seen from the outside. All adjustments to the height of the rack must be made one support at a time and only the storage compartments hidden in the side walls provide any security.
Though the prior art describes a variety of carrier racks for use with pick-up trucks, none of the prior art patents disclose a carrier rack lift assembly that can be raised and set at any desired height. Those with a degree of adjustability are limited to being set at specific levels according to the apertures in the support segments. None of the adjustable prior art rack lift means can easily be manipulated by one person. None of the prior art patents disclose an electrically powered carrier rack lift assembly that can be adjusted at the press of a button and raised to any desired height. And none of the prior art patents teach a rack lift assembly whereby any adjustment in height can be made with a full load of cargo in place. There is a need for a carrier rack lift assembly that exhibits all of the above-mentioned features and that is practical for use with all pick-up and flat bed trucks and carriers.
The present invention may provide a carrier rack lift assembly for use with pick-up trucks, flat bed trucks and trailers. The lift assembly of the instant invention may be reversibly secured to the truck bed such that it may be removed when not needed. The essence of the lift assembly may be the four electrically activated support posts which may be completely collapsible to a height of only 13 inches (33 cm) from the truck bed and may be telescoped upward to a height of 65 inches (165 cm) from the truck bed. The support posts may also be set at any desired height in between by merely pushing a button. A roof cover in the form of a traditional cap or other such cover may be used with the lift assembly, and side panels may be added to enclose an interior compartment to make it secure from inclement weather conditions and outside tampering.
It is an object of the present invention to provide a carrier rack lift assembly that can be set at any desired height without the incremental limitations requiring specific openings in the telescoping support posts.
It is another object of the present invention to provide a lift assembly that is reversibly attached to the truck bed such that it can be removed when not needed.
A further object of the present invention is to provide a lift assembly that is operated electrically so that it can be manipulated by the touch of a button.
A still further object of the present invention is to provide a lift assembly that can be operated by one person.
Another object of the present invention is to provide a lift assembly that is adjustable and permits the height to be changed with a full load of cargo in place.
A still further object of the present invention to provide a lift assembly that can support a variety of upper rail systems.
A further object of the present invention is to provide a lift assembly that can support and raise loads of considerable weight at the push of a button.
It is another object of the present invention to provide a lift assembly that can be electrically wired such that the telescoping support posts can be raised simultaneously or in any desired combination or sequence.
Another object of the present invention is to provide a lift assembly that can be used with conventional truck caps or other roof covers.
The present invention is a rack lift assembly, for use with pick-up trucks, flat bed trucks and trailers having a horizontal cargo bed, and being capable of raising and supporting an elevated utility rack. The rack assembly comprises at least four telescoping support legs, each situated at a corner of the cargo bed, and each of the support legs comprising a series of nested rotatable cylindrical segments, an outer first segment and at least one inner second segment, the first segment being smooth on its exterior surface and having at least two threads situated at the bottom of its interior surface, and the second segment being threaded on its exterior surface, having a stop means at the top of its exterior surface and a stop means at the bottom of its exterior surface, and having at least two threads situated at the bottom of its interior surface. The stop means is to prevent the segments from becoming dissociated. There is a canister for containment of the segments; a support frame to support the canister on the cargo bed; a drive shaft to rotate the segments, the drive shaft being positioned axially within the nested segments, being threaded for substantially the upper three fourths of its length, and having a stop means at its top and another stop means situated below the threads, the stop means for preventing the drive shaft from becoming dissociated from said segments. The threads on the segments and the drive shaft are of the same dimensions for cooperation therebetween. There is a means to rotate the drive shaft in a forward direction and in a reverse direction and a top cap to which the rack is affixed. When a utility rack is supported on the four support legs and the rotation means causes the drive shafts to be rotated in the forward direction the segments rotate in the forward direction and move upward such that the support legs telescope upward raising the utility rack, and when the rotation means causes the drive shaft to be rotated in the reverse direction the segments rotate in the reverse direction and are moved downward such that the support legs are collapsed and the utility rack is lowered.
The present invention is also a lift assembly for smoothly raising and lowering a load. The lift assembly comprises a series of nested rotatable cylindrical segments, an outer first segment being smooth on its exterior surface and having at least two threads situated at the bottom of its interior surface, at least one inner second segment being threaded on its exterior surface, having a collar about the top of its exterior surface and a collar about the bottom of its exterior surface and having at least two threads situated at the bottom of its interior surface. There is a canister for containment of the segments, a support frame to support the canister on a horizontal surface, a drive shaft to rotate said segments the drive shaft being positioned axially within the nested segments, being threaded for substantially the upper three fourths of its length, and having a first collar about its top and a second collar situated below the threads. The threads on the segments and the drive shaft being of the same dimensions for cooperation therebetween, and the collars on the segments and the drive shaft being capable of acting as stops to prevent said segments from becoming dissociated. There is a rotation means to rotate the drive shaft in a forward direction and in a reverse direction and a cylindrical top cap on which the load is supported. When the load is supported on the lift assembly and the rotation means causes the drive shaft to be rotated in the forward direction the segments rotate in the forward direction and move upward such that the lift assembly telescopes upward raising the load, and when the rotation means causes the drive shaft to be rotated in the reverse direction the segments rotate in the reverse direction and are moved downward such that the lift assembly is collapsed and the load is lowered.